We seek to identify novel nonpeptide macrocyclic histone deacetylase (HDAC) inhibitors as a new class of anticancer agents. HDAC inhibitors hold great promise in cancer therapy due to their demonstrated ability to arrest proliferation of nearly all transformed cell types. However, most of these agents are non-selective inhibitors of all HDAC isoforms; and a large number of the identified HDAC inhibitors have not progressed beyond preclinical characterizations. Our hypothesis in this proposal is that substitution of the peptide moiety of a prototypical cyclic- peptide HDAC inhibitor with specific non-peptidyl macrocyclic surrogates will generate a new class of potent HDAC inhibitors with improved therapeutic index. These compounds are anticipated to also possess targeted anti-cancer activity due to selective tissue distribution conferred by the appended macrocyclic moiety. In Preliminary Results a class of macrocyclic hydroxamates has been identified. The goal of this application is to study the molecular mechanisms underlying the in vitro anti-HDAC and anti-tumor activities of these compounds. Aim 1 is to develop novel nonpeptide macrocyclic HDAC inhibitors. The first step here is to broaden our design approach to include other structurally similar macrocyclic templates in order to create a tool set upon which subsequent structure activity relation (SAR) studies will be based. To guide this effort, we will use molecular docking (AutoDock) to investigate the SAR of the combination of these macrocyclic templates with key HDAC inhibitor pharmacophores. Aim 2 is to characterize the structural and biochemical requirements for in vitro and whole cell HDAC inhibition. Toward this end, we will profile the anti-HDAC activity of compounds obtained from the priority list generated by the docking experiments using both in vitro HDAC inhibition assay and whole cell activity in human lung cancer cell lines. Moreover, we will evaluate the whole cell mechanism of our potent inhibitors based on intracellular status of p21WAF1/CIP1 and HDAC7 genes, and histone protein acetylation patterns. Our Aim 3 is to investigate the organ distribution and in vivo efficacy of lead compounds in mice. We will first study compound organ distribution behavior in healthy male Balb/c mice. Compounds displaying lung selective accumulation with good pharmacokinetic parameters will then be advanced to in vivo efficacy studies in Balb/c (nu/nu) mice bearing xenograft models of specific lung cancers. In the longer term, we will identify series of novel HDAC inhibitors that will be advanced to further preclinical/clinical evaluations. Additionally, the proposed studies will yield new insights on the roles of HDACs in the etiology of cancer. PUBLIC HEALTH RELEVANCE: Lung cancer is the leading cause of cancer deaths in the US. Outlined in this proposal is a method that will enable identification of new classes of chemotherapeutic agents that possess lung- selective anti-cancer activity for targeted lung cancer therapy applications. Our proposed approach is expected to lead to chemotherapeutic agents with superior therapeutic indices and will significantly impact patient survival prognosis and positively contribute to human health management.